炎症状态下分泌型磷脂酶A2（sPLA2）调控牙龈上皮角化的机制研究

The degree of gingival epithelial keratinization in the inflammation condition is reduced or even lost, but the prevention or treatment is difficult for its unclear regulatory mechanisms. Secretory phospholipase A2 (sPLA2) is a key factor produced by inflammatory cells that can influence lipid metabolism in the epithelium or epidermis. It has been found that the level of phospholipase A2 (phospholipase A2) is increased in some inflammatory proliferative skin diseases, but the regulatory mechanism is still unclear. Our previous study has also demonstrated that sPLA2 level in the spinous layer and basal layer of inflammatory gingival epithelium was higher than that in the healthy control group, which was negatively associated with cell ketatin 10 level. Moreover, we have demonstrated that the amount of lysophosphatidylcholin (lysoPC), produced mainly by PLA2, in the inflammatory gingival tissue also increasesd compared with that in the healthy periodontal group. Cell membrane channel Orai1 is a calcium influx channel may be activated by PLA2/ arachidonic acid, which may induce cell proliferation and inhibit nuclear autophagy through mTOR. In order to study whether sPLA2, as a key factor, regulates the differentiation/keratinization of gingival epithelium in the inflammatory state, we will focuse on the following studies: A. the level of sPLA2 in the gingival epithelium under the inflammatory condition and its relationship with epithelial differentiation/keratinization; B. whether sPLA2 inhibitor will promote the keratinization of gingival epithelium in the inflammatory environment; C. the regulatory mechanism of sPLA2 influence the gingival epithelial differentiation/keratinization. As a secretory molecule, sPLA2 is an important target for clinical diagnosis and intervention therapy. This study is expected to provide a theory for the prevention and treatment of gingival keratinization abnormity or deficiency.

炎症中牙龈上皮角化程度降低甚至丧失，因其调控机制不清而难以预防和治疗。分泌型磷脂酶A2（sPLA2）是由炎症细胞产生可影响脂质代谢的关键因子。我们前期研究发现炎症牙龈上皮中sPLA2水平较高，与细胞角蛋白10水平呈相反关系。在大量炎性增生性皮肤疾病中也发现sPLA2表达水平升高，其调控机制不清。PLA2/花生四烯酸可以激活细胞膜通道Orai1促进钙内流，可能进而激活mTOR引起细胞增殖，抑制分化和核自噬。为了研究炎症状态下sPLA2是否作为一个关键因子调控牙龈上皮的分化/角化，本项目在前期研究基础上重点探讨：①炎症环境下牙龈上皮中sPLA2的水平以及与上皮角化的关系；②抑制sPLA2活性是否可以促进牙龈上皮角化；③sPLA2参与调控牙龈上皮分化/角化的分子机制。sPLA2作为分泌型分子，是干预性治疗的重要靶点。本课题有望为预防和治疗角化牙龈缺乏，促进上皮角化提供新的思路和理论依据。

角化龈的重要性越来越得到广大口腔医师的关注，炎症中牙龈上皮角化程度降低甚至丧失，但是牙龈角化在牙周炎症环境下的调控机制不清而难以预防和治疗。分泌型磷脂酶A2（sPLA2）是由炎症细胞产生可影响脂质代谢的关键因子。我们的研究围绕①慢性牙周炎症状态下牙龈组织中sPLA2和脂质代谢物的变化，及其相互关系；② sPLA2对人角质形成细胞分化/角化的影响，探讨了其中的机制；③以大鼠实验性牙周炎为模型，研究了sPLA2和牙龈上皮角化的关系。发现了以下结果：①sPAL2及其两种亚型PLA2G2A和PLA2G2D在慢性牙周炎组的水平显著高于临床牙周健康对照组。脂质谱分析也发现sPAL2.下游的脂质代谢物溶血磷脂酰胆碱（lysoPCs）的水平在慢性牙周炎患者牙龈组织中显著升高，这进一步证实sPLA2在炎症环境中水平升高。同时确定了20种差异表达的脂质代谢物，在慢性牙周炎组溶血磷脂酰胆碱（lysoPCs）、二酰甘油（DGs）和磷脂酰乙醇胺（PEs）显著上调，而甘油三酯（TGs）则显著下调。②建立了大鼠实验性牙周炎模型，发现在炎症组PLA2G2D在牙龈上皮中的表达水平显著升高。③ 不同浓度sPAL2刺激人角质形成细胞不同时间后发现12小时内对细胞分化的影响不显著，而24小时则随着sPAL2浓度（0.25,0.5和1ug/ml）升高角化标志物Krt10，IVL，TGM1的表达显著降低。sPLA2可以显著促进细胞内钙离子升高，但是对Orai1表达的影响不显著，可能通过上调p-p38和p-ERK抑制细胞分化。④ sPAL2刺激人角质形成细胞24小时，促进甘油三酯降解的关键酶ABHD5表达量显著升高，呈剂量依赖型。角质形成细胞在甘油三酯的刺激下在高钙和低钙环境中角化标志物的表达都显著升高，且呈剂量和时间依赖型，表明sPLA2可能通过上调ABHD5促进甘油三酯分解来抑制细胞分化/角化。